package test.test6_22;

import java.util.Scanner;

/*
计算n条直线最多能把平面分成多少部分？ n >= 1
 */
public class Demo2 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int i = sc.nextInt();

        if(i < 0) {
            System.out.println("输入不合法");
        }else {
            System.out.println(new Demo2().method(i));
        }
    }
    public int method(int i)  {
        return i*2;
    }
}


